Fluorouracil (5-FU), also known as adrucil, is a chemotherapy agent that functions by blocking the production of DNA, which inhibits cell division and thereby prevents tumor cells from dividing and growing. 5-FU acts in several ways, but principally as a thymidylate synthase (TS) inhibitor. Interrupting the action of this enzyme blocks synthesis of the pyrimidine thymidine, which is a nucleoside required for DNA replication. TS methylates deoxyuridine monophosphate (dUMP) to form thymidine monophosphate (dTMP). Administration of 5-FU causes a scarcity in dTM. Thus, rapidly dividing cancerous cells undergo cell death due to lack of thymine. High levels of TS can overcome the effects of 5-FU while high levels of the TYMP protein promotes the activity of 5-FU.
Leucovorin calcium (LV), also known as folinic acid, potentiates the growth inhibitory effects of 5-FU. LV is a precursor for 5,10-methylene-tetrahydrofolate (CH2-THF) and CH2-THF enhances the inhibition of TS by the 5-FU metabolite FdUMP.
Oxaliplatin, also known as eloxatin, is a cancer chemotherapy agent that interferes with DNA replication, thus preventing cells from dividing and leading to tumor cell death via apoptosis. Oxaliplatin is thought to form platinum-DNA adducts in tumor cell DNA, that appear to be more effective at blocking DNA replication and are more cytotoxic than adducts formed from cisplatin. The damaged DNA elicits DNA repair mechanisms, which in turn activate apoptosis when repair proves impossible thus killing the tumor cells.